AMS data
Description
Table S1. Summary of magnetic scalar and directional data in the Longmen Shan thrust belt.
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We collected samples from 128 sites along the designated transects across the LSTB using a gasoline-powered portable drill. From each site, we collected at least five rock core samples that included mudstones, siltstones, sandstones, limestones, slates, and phyllonites. All the rock core-samples were oriented using a compass–clinometer, with dip directions and dip angles marked on each sample. For AMS analysis, each sample was cut to the dimensions of a standard cylinder 25 mm in diameter and 22 mm in height. The AMS was measured on an average of 11 standard cores per site and a total of 1462. To interpret the tectonic significance of the AMS data, it is vital to correctly identify the magnetic minerals responsible for the AMS (Chadima et al., 2004; Haerinck et al., 2013; Hrouda et al., 2018). Five samples were selected for acquisition and backfield demagnetization of isothermal remnant magnetization (IRM) and producing temperature-dependent susceptibility (k–T) curves, which were used to determine the magnetic carrier minerals that contributed to the AMS. The above experiments were carried out at the Paleomagnetism and Environmental Magnetism Laboratory, China University of Geosciences, Beijing. We measured the AMS ellipsoid orientation in 1462 oriented standard rock cores using an AGICO MFK1-FA Kappabridge susceptibility meter with a typical sensitivity of ~2.0 × 10−8 SI under a magnetic field of 200 A/m and at a frequency of 976 Hz (Jelínek, 1981). The IRM acquisition and backfield demagnetization of IRM were performed using an ASC IM-10-30 impulse magnetizer and a JR-6A spinner magnetometer. The k–T curves of crushed specimens weighing ~250 mg were obtained in argon by using a KLY-3S Kappabridge with a CS-3 high-temperature furnace. The AMS data and k–T curves were processed by the ANISOFT 4.2 software (Chadima & Jelínek, 2009) and the Cureval 8.0 software of AGICO (Chadima & Hrouda, 2009), respectively.